竖向荷载对月球车行驶性能影响的离散元分析

Investigation of the Vertical Load Effects on Lunar Rover Trafficability Using DEM

技术的发展使得月球车原材料强度更高、质量更轻,而复杂的探测任务要求月球车携带的探测设备越来越多。为了平衡月球车承受的荷重,防止月球车车轮因承受荷载不当导致在月面打滑、下陷以致不能正常行驶,有必要研究月面环境下竖向荷载对月球车行驶性能的影响。针对真实月壤内摩擦角较大、有粘聚力的特点,采用笔者提出的一种考虑粒间抗转动作用与粒间范德华力两个因素的月壤散粒体力学接触模型,模拟月面环境下三种竖向荷载P作用下月球车刚性驱动轮与月壤的相互作用问题。其中,当竖向荷载为400/6 N时,车轮打滑,因此,文中主要对竖向荷载为1 000/6 N和1 350/6 N两种情况进行对比分析。研究结果表明:月面环境下,滑转率随竖向荷载的增加呈下降趋势,月球车因为轮上荷载过小,导致滑转下陷过大而失去行走能力的风险更高。沉陷量也随竖向荷载的增加而减小,月面环境下荷载过小会使月壤的可通过性变差。月面环境下牵引效率随竖向荷载增大而升高但都保持在较低水平。

The material used in rover vehicle gets lighter while the increasing detection equipments carried by lunar rover add the weight. In such problems,the rover may get stuck and even cause failure of an exploration mission because of unreasonable load exerted on the wheel. To avoid such problems,it＇s essential to investigate the vertical load effects under lunar environment. The internal friction angle of lunar soil is quite large,accompanied by small cohesion. In this paper,particle rolling resistance and van der Waals forces between lunar soil particles are taken into consideration in the new lunar soil contact model. With this model the interactions between rigid wheel of lunar rover and lunar soil are simulated by DEM under three vertical loads（ 400 / 6 N,1 000 / 6 N and 1 350 / 6 N）. The results show that the slip ratio of the wheel decreases with the vertical load and the smaller load tends to increase the risk of failure under lunar surface. Lunar environment is unfavorable to the trafficability of lunar rover when the vertical load is small. The tractive efficiency in the lunar environment increases with the load,but all are at a relative low level.